• Optical Terms and Definitions

    1. 20-20 Vision - Normal visual acuity. Upper number is the standard distance (20 feet) between an eye being tested and the eye chart; lower number indicates that a tested eye can see the same small standard-sized letters or symbols as a normal eye at 20 feet.
    2. Amblyopia or "lazy eye" - Condition of decreased vision in one or both eyes without detectable anatomic damage in the eye or visual pathways. Usually NOT correctable by eyeglasses or contact lenses.
    3. Astigmatism - Optical defect in which refractive power is not uniform in all directions (meridians). Light rays entering the eye are bent unequally by different meridians, which prevents formation of a sharp image focus on the retina. Slight uncorrected astigmatism may not cause symptoms, but a large amount may result in significant blurring and headache.
    4. Cataracts - The clear lens you are born with in each eye develops a yellowing or haziness over time, which is a cataract.  Cataracts scatter light and increase glare.  While keeping your eyeglass prescription up to date and using polarized sunglasses helps a lot, these things can’t fully overcome all the glare when a cataract is present.
    5. Conjunctivitis - Conjunctivitis is an inflammation or infection of the conjunctiva, the thin transparent layer of tissue that lines the inner surface of the eyelid and covers the white part of the eye. Conjunctivitis, often called “pink eye”, is a common eye disease, especially in children. It may affect one or both eyes. Some forms of conjunctivitis can be highly contagious and easily spread in schools and at home. While conjunctivitis is usually a minor eye infection, sometimes it can develop into a more serious problem which is why it is recommended that individuals with conjunctivitis seek medical treatment.   Conjunctivitis may be caused by a viral or bacterial infection. It can also occur due to an allergic reaction to irritants in the air like pollen and smoke, chlorine in swimming pools, and ingredients in cosmetics or other products that come in contact with the eyes. Sexually transmitted diseases like Chlamydia and gonorrhea are less common causes of conjunctivitis.
    6. Convergence Insufficiency - An eye coordination problem in which your eyes have a tendency to drift outward when reading or doing close work. This is a condition in which the muscles of the eye responsible for convergence (turning the eyes in) appear to be weak, at least relative to the muscles responsible for divergence (turning the eyes out). Convergence insufficiency is a common condition that is characterized by your inability to maintain proper binocular eye alignment on objects as you approach from distance to near. This results in strained eyes and headache, eyestrain, blurred vision, or fatigue with continued efforts at near work.
    7. Cornea - Your cornea is the clear “dome” over the colored part of the eye. It is covered by a tear layer, and the tears function as a part of the optical system of your eye.  Having dry eyes (reduced or poor tear quality) causes the quality of your eyesight to suffer.  As you mature, your eyes typically produce fewer natural tears, making this problem worse.  The heating and air conditioning vents can also severely dry out your eyes while driving if they are pointed directly at the face.  A dry ocular surface will increase glare and create an irregular optical surface for light to pass through into the eye. Do not dismiss dry eyes if you are a sufferer.  Talk to Wohl Optics about over the counter and prescription treatments available.
    8. LASIK Acronym for LAser in SItu Keratomileusis. Type of refractive surgery in which the cornea is reshaped to change its optical power. A disc of cornea is raised as a flap, then an excimer laser is used to reshape the intrastromal bed, producing surgical flattening of the cornea. Used for correcting myopia, hyperopia, and astigmatism.
    9. Myopia - nearsightedness - Focusing defect in which your eye is overpowered. Light rays coming from a distant object are brought to focus in front of the retina. Requires a minus lens correction to "weaken" the eye optically and permit clear distance vision.
    10. Presbyopia - Refractive condition in which there is a diminished power of accommodation arising from loss of elasticity of the crystalline lens, as occurs with aging. Usually becomes significant after age 45.
    11. Pupil - Your pupil is not actually a structure of the eye, but rather it’s the black hole which allows light into the eyes. Your pupils naturally become smaller as you mature.  It is common for your pupils to be half the diameter at age 70 of what they were at age 20. This reduction in pupil size decreases the amount of light entering your eye, requiring brighter light conditions to see well as you mature.  While it seems contradictory to wear sunglasses when your pupils are smaller and require more light, wearing polarized sunglasses is important as you mature.  In bright light, your pupils naturally constrict further.  A small pupil will become even smaller when it’s bright. By wearing sunglasses, the darkening effect of the tinted lens prompts your pupil to remain larger, allowing more light to enter your eye.
    12. Refraction - Test to determine an eye's refractive error and the best corrective lenses to be prescribed. Series of lenses in graded powers are presented to determine which provide sharpest, clearest vision.
    13. Retina - The retina is the lining on the inside of your eye where light is ultimately focused. While dozens of conditions can affect your retina and reduce your ability to see well when driving, perhaps the most well-known condition is Age-Related Macular Degeneration (AMD.)  Early signs of AMD are often first detected during an eye examination, prior to you ever being aware of its presence.  Cigarette smoking is linked to AMD, as is Ultraviolet light exposure.  Seeing your eye care provider at Wohl Optics regularly will help detect early signs of condition and multiple avenues to help mitigate its effects will be discussed by the doctor.
    14. Schlera - Opaque, fibrous, protective outer layer of the eye ("white of the eye") that is directly continuous with the cornea in front and with the sheath covering optic nerve behind.